The invention relates generally to monitoring the system environment of an inactive networked computer, and more specifically to transmitting frame data in response to system events.
Local Area Networks (LAN""s) consist of a group of interconnected computers communicating according to a common protocol such as Ethernet (IEEE Standard 802.3). In a client-server type LAN, a server computer maintains files, which may be accessed by client computers. The server may also monitor and perform various maintenance functions on the client computer.
To save energy and reduce costs, client computers may enter a reduced-power (or sleep) state when they are not in active use. A sleep state shuts-down most components of a client computer and maintains only minimal functionality. Various techniques have been implemented to allow a server computer to wake-up a sleeping client computer. Generally these techniques require the sleeping computer to monitor network activity. Specific network events wake-up the sleeping computer.
Many network routers maintain a cache of active network computers. When a computer enters a sleep state it is no longer active on the network. Therefore, after a sufficient time, its address will age-out of the network router""s cache. Upon receipt of a packet having an address not in its cache, the router will issue an address resolution protocol request (ARP).
The ARP is one network event, which should wake-up the sleeping computer. Upon entering an active state, the computer responds to the ARP and the network router continues to maintain the computer""s address as an active network node.
Unfortunately, the wake-up time of the sleeping computer may exceed the time allowed to respond to the ARP. When this occurs, the router will drop the computer""s address as an active network node. The router also will drop any subsequent packets addressed to that node.
In addition to monitoring network activity, a sleeping computer may monitor other events. For example, a sleeping computer may monitor system voltages. Upon detection of a change in status, such as an error condition, the sleeping computer may wake-up. The computer may then report the change in status over the network. The computer may then return to the sleep-state.
Few sleep-state monitoring systems include transmit capabilities, redundant to those of it""s host computer, due to the expense associated therewith. The sleep-state monitoring systems rely upon the host computer to transmit change in status information. Unfortunately, an error condition may debilitate a sleeping computer. Thus, even though the monitoring system of a sleeping computer is able to detect an error condition, the sleeping computer may be unable to enter an active state to transmit the error condition over the network.
Few sleep-state monitors include an independent transmit system due to cost constraints and to the added complexity. For example, a typical transmit system requires logic to implement access to a first-in first-out buffer. Moreover, a typical transmit system implements direct memory access.
According to one aspect of the invention a network interface suitable for transmitting frame data over a network includes a media access control, a buffer manager and a memory. The media access control provides a connection to a media interface. The buffer manager is operationally coupled with the media access control. The memory is operationally coupled with the buffer manager. The buffer manager is configured to read frame data from the memory and provide the frame data to the media access control.
According to another aspect of the invention, a transmit buffer memory is configured to transmit a frame of data over a network. The transmit buffer memory receives frame data from a processor. The transmit buffer memory provides the frame data to a buffer manager only after an entire frame has been received.
According to another aspect of the invention a controller suitable for monitoring events related to a computer system includes a control processor, a plurality of connections, and a network interface. The control processor is configured to communicate with a host processor. The plurality of connections are operationally coupled with the control processor, and the controller processor is configured to monitor system events over the plurality of connections. The network interface is operationally coupled with the control processor and has a memory. The memory receives frame data from the control processor.
According to another aspect of the invention, a computer system has a network interface. The computer enters a reduced power state. The computer system monitors system events. The computer system writes a frame to a memory wherein the frame contains data relating to a system event while in the reduced power state. The computer system transmits the frame over a computer network while remaining in the reduced power state.
These and other objects, features and advantages will become apparent when considered with reference to the following description and the accompanying drawings.